38 



THE GASES IN ROCKS. 



TABLE 27. 



The analyses of meteorites by Wright show that, in all cases, carbon 

 dioxide reached a higher percentage in the gas evolved at 500 than it 

 did in that obtained at red heat, and that the reverse of this was true of 

 hydrogen in the stony meteorites. In the iron meteorites, however, two 

 analyses indicated a marked fall in hydrogen with the increase of heat, while 

 the other two were characterized by an increase. Wright's figures for the 

 meteorite from Guernsey County, Ohio, illustrate the continuous decrease 

 in the percentage of carbon dioxide: At 100, 95.92 p. ct.; at 250, 86.36 p. 

 ct.; at 500, 82.28 p. ct.; incipient red heat, 33.55 p. ct.; red heat, 19.16 p. ct. 



The volume of gas obtained at each temperature is only stated for 

 500 and red heat. These show that up to 500, 2.06 volumes were evolved, 

 and that above this point only 0.93 volume was received. From this it 

 appears that the diminishing percentages of carbon dioxide above 500 

 represent an absolute slackening of the output of that gas, as well as an 

 apparent decrease due to the greater evolution of hydrogen. It might 

 be argued that in this case, where gas was produced at only 100, the 

 cavities contributed the carbon dioxide, yielding it early and then slacken- 

 ing, as would be expected; but even if this be admitted, the hydrogen 

 manifestly can not be ascribed to that source. Tending in a measure to 

 support this view is the work of Sorby, 1 who has shown that olivine crystals 

 in the meteorites of Aussun and Parnallee, when examined under the micro- 

 scope, contain numerous small cavities filled with gas, similar to those which 

 have been observed in many terrestrial minerals. 



In his earlier paper, Wright expressed the opinion that the gases were 

 partly condensed upon the particles of iron and partly absorbed within 

 them. Later he took the position that while some gas may be condensed 

 upon the fine particles of iron, a large part of the carbon dioxide, and prob- 

 ably also of the other gases, is mechanically imprisoned in the substance of 

 the meteorite. This view, which does not seem to be in accord with his 

 researches at different temperatures, he bases largely upon a single experi- 

 ment. Material from the Iowa meteorite was finely pulverized and the 

 iron grains separated from the non-metallic powder. A third portion 

 consisted of coarse fragments of the meteorite. The three portions heated 

 for the same time gave the following results: 



TABLE 28. 



1 Sorby, Proc. Roy. Soc., vol. 13 (1864), pp. 333-334. 



